"I will keep going because I think these are good reforms," he told reporters on the sidelines of the G7 summit in Japan, adding that his government would ensure "freedom of movement" for citizens beset with rail strikes and fuel blockades.
Meanwhile, French unions on Friday urged workers to step up a wave of industrial action against a controversial labour law, a day after clashes over the reform rocked potests in Paris.
With just two weeks to go before France hosts the Euro 2016 football championship, the country has been gripped by more than a week of rolling strikes that have disrupted transport and sparked fuel shortages.
The tug of war between unions and President Francois Hollande's deeply unpopular government showed little sign of ending, as union representatives urged workers to "multiply and support" the strikes.
They said the government's response to the strikes and its "stubbornness" in not withdrawing the contested law was only "boosting the determination" of opponents to the legislation.
The call came a day after police fired tear gas at a small group of masked youths who smashed shop windows and parked cars in central Paris, in the latest outburst of anger at the controversial legislation.
Nationwide protests Thursday saw 153,000 people take to the streets overall, officials said, though union leaders put the number at 300,000.
French authorities said 62 demonstrators were taken into custody across the country, 32 of them in the capital, while 15 security officers were injured in clashes.
One person was badly hurt in the unrest in Paris and had to be hospitalised, police said. Interior Minister Bernard Cazeneuve called for a probe into the incident that led to the man's injuries.
Although some blockades on fuel depots and refineries in the north of the country were called off, many motorists were still stuck in long queues at petrol stations around France.
A man in his 50s had to be airlifted to hospital after a motorist rammed a roadblock outside a petrol refinery at Fos-sur-Mer on the Mediterranean coast.
The government has been forced to tap into its strategic reserves and Hollande has vowed to do "everything... to ensure the French people and the economy is supplied".
At the Tricastin nuclear plant in southern France, workers set fire to piles of tyres on Thursday, sending clouds of black smoke into the sky.
Unions are furious about the legislation forced through parliament aimed at reforming France's famously rigid labour laws by making it easier for companies to hire and fire workers.
Many organisations, including the International Monetary Fund, have said the labour legislation is necessary to create jobs.
But unions are demanding the reforms be scrapped altogether, arguing they favour business at the expense of workers' rights and are unlikely to bring down high unemployment.
They have called for rolling strikes on the Paris Metro to start on the day of the opening match of the European Championships on June 10.
Prime Minister Manuel Valls has insisted the legislation will not be withdrawn, but says it might still be possible to make "changes" or "improvements".
But there were signs that some in the ruling Socialist Party were buckling, with Finance Minister Michel Sapin suggesting the most contested part of the legislation should be rewritten.
Valls slapped Sapin down and ruled out revamping the clause, which gives individual companies more of a free hand in setting working conditions.
"You cannot blockade a country, you cannot attack the economic interests of France in this way," a defiant Valls told parliament, after earlier branding the hardline CGT union that is driving the protests "irresponsible".
The mounting problems for the government come 12 months ahead of an election in which Hollande is considering standing again despite poll ratings that are among the lowest for a French leader in modern history.
The CGT said staff at all but three of France's 19 nuclear power stations -- which provide three-quarters of its electricity -- have voted to stop work.
RTE, the body overseeing the national power network, said the stoppages were not having an immediate effect on the electricity supply, but "if it worsens, it will have an impact on the management of the network".